FRACTURE STRESS ANALYSIS OF ALUMINA MATRIX WITH ZIRCONIA NANOGRAINS FOR SPACE APPLICATIONS

Reference Presenter Authors
(Institution)
Abstract
09-113 Renata Lopes Gonçalves Souza Souza, R.L.(Instituto Nacional de Pesquisas Espaciais); Nono, D.A.(Instituto Nacional de Pesquisas Espaciais); Mendes, J.P.(Instituto Nacional de Pesquisas Espaciais); Silva, I.C.(Instituto Nacional de Pesquisas Espaciais); Nono, M.C.(Instituto Nacional de Pesquisas Espaciais); Structural ceramic materials for space applications must have high reliability in their properties values. In ceramic composites with more than one component, the dispersions of mechanical properties values of ceramics are directly related to the chemical composition and to degree of microstructure homogeneity. This homogeneity must be obtained in the mixing step of the component powders. In this work, fracture stress analyzes of alumina-zirconia ceramic composites (ZTA composites) with different amounts of zirconia are presented. Ceramics with 5, 8.5, 12, 15.5 and 18.5 wt% were obtained from the mixture of deflocculated suspensions of microparticulate alumina and nanoparticulate zirconia. The powders mixtures were compacted by isostatic pressing of 200 MPa and the sintered ceramics at 1550 oC for 2 hours. The sintered ceramics characterized by X-ray diffraction to confirm the formation of the Al2O3-ZrO2 composite. The ceramics were submitted to the flexural tests in 4 points to obtain the fracture stress values. The results were analyzed using Weibull statistics. The results show a tendency to decrease the Weibull's modulus by increasing the amount of ZrO2. This result was associated to the increase in the amount of larger zirconia grains.
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